The present invention relates generally to the art of railway cars. More particularly, the invention pertains to greaseless fulcrums for gear-operated railway car doors. The invention is particularly applicable to plug-type metal doors of the type used on railway freight cars and will be particularly described with reference thereto. However, it will be appreciated by those skilled in the art that the invention has broader applications and is adaptable to use with doors of other types and in other environments.
Rectangular metal doors of a known type used in railway cars include a generally rectangular frame typically comprised of top, bottom, horizontal stiffeners, and opposed side members. Metal panels are secured to these frame members for completing the basic door construction. In most conventional railway cars, the frame members and metal panels are riveted and/or welded together.
Railway car doors are typically classified as either sliding doors or plug doors. Of the two, sliding doors are less complex, having a door configured to slide back and forth within a side panel of a railway car to selectively open and close an opening defined therein. Plug doors are more complex in that they are configured to first move laterally out of the opening defined in the railway car and then move longitudinally along a track disposed adjacent the railcar side panel.
Plug doors to be mounted on the side of a railcar include a series of panels or sheeting reinforced by horizontally disposed channels at the top, bottom and/or intermediate portions of the door. A pair of vertically-oriented elongated support members such as pipes, rods or bars are configured to support the door on the railcar. The support members are typically provided with upper and lower cranks attached to the ends thereof which serve as lever arms for laterally moving the door into and out of the railcar door opening. Upon actuation of a driving mechanism, such as a manually operated gear assembly, the support members are rotated causing corresponding rotation of the cranks. Rotation of the cranks, in turn, draws the door laterally outward from the opening until the door is supported on a track disposed adjacent the side of the railcar. The door is moveably supported on the track by roller hangers which enable the door to slide longitudinally along the side of the railcar.
The support members are rotatably mounted to the door via a plurality of brackets or fulcrum assemblies disposed on the door along the length of the support members. The fulcrum assemblies generally include an outer shell or cover member surrounding a lubricant fitting for holding a lubricant. Grease is commonly used as the lubricant for providing substantially friction free rotation of the support members within the fulcrum assemblies. Although grease has long been used as a lubricant for the support members, it has several disadvantages.
One disadvantage resides in the fact that grease is difficult to maintain and seal and, thus, often leaks or escapes from its intended working environment. As a result, grease filled fulcrums must be continuously monitored to ensure that the grease has not escaped. A second disadvantage is that grease degrades over time, especially when exposed to harsh environments such as those experienced by railcars. As a result, the grease must be periodically replaced.
Conducting periodic maintenance is quite cumbersome and sporadic because there is no easy and convenient place for performing maintenance on railcars and no simple tracking method for determining when such maintenance should be undertaken. Typically, railcars remain in service for extended periods of time, thereby making it difficult to monitor and maintain the fulcrum assemblies. A third disadvantage is the fact that it is relatively expensive to maintain grease filled fulcrums, especially when the cost is calculated over the life of the railcar.
Accordingly, it has been considered desirable to develop a fulcrum assembly for plug-type railcar doors that addresses the foregoing difficulties and others while providing better and more advantageous overall results.
In accordance with the present invention, a greaseless fulcrum for a railcar door is provided. The railcar door includes a substantially planar wall. At least one elongated support member, such as a pipe or rod, has first and second terminal ends, and is rotatably mounted to the door. A drive mechanism for imparting a rotational force to the support member is operatively associated with the door. At least one greaseless and oil-free fulcrum is operatively connected to the support member for rotatably mounting the support member to the sheeting. The fulcrum includes a self-lubricating insert substantially surrounding a portion of the support member.
In accordance with a more specific aspect of the invention, the greaseless and oil-free insert is comprised of a self-lubricating material. The insert is dimensioned to substantially surround an axial portion or segment of the support member. The fulcrum further includes a filler which partially surrounds the insert and is dimensioned to be secured to the railcar door. A cover is provided which also partially surrounds the insert and is dimensioned to likewise be secured to the railcar door.
According to more limited aspects of the invention, the insert may comprise a one piece member having means cooperating with the filler and/or cover to prevent axial shifting therebetween, or may comprise single or multiple members secured to an associated door along with the filler and cover themselves.
In accordance with still another aspect of the invention, a method of rotatably mounting a support member to a railcar door via a greaseless and oil-free fulcrum is provided. The method includes the steps of substantially surrounding the support member with at least a portion of an insert made from a high-density polyethylene material, placing a portion of a filler in cooperating relation with a portion of the insert, positioning a portion of a cover in cooperating relation with a portion of the insert, and then securing the filler and cover to a railcar door.
A principal advantage of the present invention resides in the provision of a fulcrum assembly which operates effectively without the use of grease.
Another advantage of the invention is found in the provision of a fulcrum assembly that is relatively easy to maintain.
Another advantage of the invention resides in the provision of a fulcrum assembly that is relatively low in cost.
Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification.